textproduct: Quad Cities

KEY MESSAGES

- Low-end chance for an isolated strong-severe storm tonight into Sunday morning, largely between midnight and sunrise. Main hazard will be hail, with frequent lightning and brief heavy rainfall.

- A prolonged period of very hot and humid conditions will be seen Sunday through the upcoming work week, with peak heat index values upwards to 105 degrees or higher. Extreme Heat Watches and Warnings have been issued for this upcoming hot spell.

- Precipitation chances will remain limited through midweek, increasing each day from Thursday onward. The chance for showers/storms and resultant cloud cover may have an impact on forecast high temperatures as we approach the July 4th weekend.

SHORT TERM /THROUGH SUNDAY/

Issued at 142 PM CDT Sat Jun 27 2026

Weak upper wave passes through the Northern Plains and Upper Mississippi River Valley tonight into Sunday AM. With this, we will have a stationary boundary just south of our area this afternoon through tonight, which will start to push northerly as the aforementioned wave moves out and strong ridging overtakes the region through Sunday. As this boundary pushes north late tonight, a 25-35 KT LLJ will converge into it, allowing for isolated-scattered showers and storms late tonight into Sunday AM. Confidence is low, especially on coverage. Current guidance favors areas south of Highway 34 for storm chances, with those north of the highway likely remaining dry. Overall PoPs are lower, ranging between 20-40% along/south of Highway 34. There remains a low-end severe threat south of Highway 34, where the SPC has a Marginal Risk, level 1/5. Due to lower shear, confidence in the severe threat is low at this time. Although, a strong to severe storm cannot be ruled out, where hail would be the main threat. Frequent lightning and brief heavy rainfall will also accompany any storm. Around sunrise on Sunday, shower and storm activity should be waning or moved out of the area already. Increasing cloud cover through the night will keep low temperatures in the mid-upper 60s.

Sunday, we will see cloud cover start to decrease from southwest to northeast. Although, we will continue to see a mix of clouds/sun for much of the area through Sunday. With the aforementioned boundary now pushing well north through our area during the day, strong warm advection will allow for increasing temperatures and moisture. Temperatures tomorrow will increase into the upper 80s to low 90s, especially for areas south of Highway 20. These unseasonably warm temperatures will couple with dewpoint temperatures in the mid 70s, creating very hot conditions. The high humidity and temperatures will result in heat index vales nearing 100 or higher. Thus, it will be important to take necessary precautions and limit time out in the heat tomorrow. Opted to upgrade a large portion of our Extreme Heat Watch to an Extreme Heat Warning, owing to the potential for multiple days with heat index values forecast at 100 or higher. There will be several locations that see heat index values around 105 or higher as well a couple of these days, where overnight ambient low temperatures will be at least 75 degrees. Uncertainties in max temperatures Sunday in our north/northeast remain, resulting in us holding onto the Extreme Heat Watch at this time due to cloud cover impacts on temperatures.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 142 PM CDT Sat Jun 27 2026

Strong upper ridge will remain over the Central CONUS, keeping the heat dome overhead through midweek at least. Under this heat dome, air temperatures will remain in the low-mid 90s, coupled with dewpoints in the 70s. Thus, very hot to oppressive heat at times can be expected, with peak heat index values between 100-110. There remains some uncertainty on these values, given the storm track being closer to our area. The current storm track is generally over western and central Iowa, which should keep us just outside of the storms, possibly grazing our northwest (15-30% PoPs). Although, some cloud debris can result in slight fluctuations to the temperatures. Either way, it will be hot and humid through midweek.

Thursday onward through the holiday weekend, we will start to see the strong ridge over the Central CONUS break down a little and start to shift east. This easterly shift will result in upper waves tracking closer/over our area, leading to increasing precipitation chances. Thus, there are uncertainties in the temperature forecast as we approach the July 4th weekend. Overall, we are expected to remain hot and humid. If we avoid the storm track, it is possible that the oppressive heat will continue, but if we fall under the storm track, temperatures may be lower than currently forecast. Currently, precipitation chances are not very high, but we do have 20-40% PoPs each day Thursday onward. Forecast would favor the potential for diurnally driven storms with such hot and humid conditions, with the chance for overnight ring of fire convection that may result in convective debris into the daytime. This convective debris would be a limiting factor on the high temperature forecast.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1159 AM CDT Sat Jun 27 2026

This afternoon, we will continue to see the low clouds scatter and increase in height. Currently, we are seeing cigs between 1000-2500 ft throughout much of the area (scattered-broken), with BRL still seeing broken-overcast cigs between 500-1000 ft. By 00z, cigs at BRL should improve, resulting in much of the area remaining VFR until at least 06z. Between 06-12z, increasing warm advection pushes into the area, bringing another bout of low clouds, along with the chance for isolated- scattered showers/storms. Some uncertainty remains on precipitation chances, prompting a PROB30 group at this time. Cigs may drop as low as 1000-1500 ft as these pass through, with gradual improvements throughout between 12-15z from south to north. Winds will largely remain out of east-southeast around 10 KTs, increasing after 15z Sunday with gusts upwards to 20-25 KTs by midday.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Extreme Heat Watch from Sunday afternoon through Tuesday evening for IAZ040>042-053-054-066. Extreme Heat Warning from 1 PM Sunday to 9 PM CDT Tuesday for IAZ051-052-063>065-067-068-076>078-087>089-098-099. IL...Extreme Heat Watch from Sunday afternoon through Tuesday evening for ILZ001-002-007-009-016>018. Extreme Heat Warning from 1 PM Sunday to 9 PM CDT Tuesday for ILZ015-024>026-034-035. MO...Extreme Heat Warning from 1 PM Sunday to 9 PM CDT Tuesday for MOZ009-010.